Characterization of PrPSc transmission from immune cells to neuronal cells

We investigated PrPSc transmission in neuronal cells, spleen cells and several immune cells using an in vitro cell-to-cell transmission system. The transmission of PrPSc in the supernatant of PrPSc-infected neuronal cells was also investigated. We found that PrPSc transmission was more efficient in the cell-to-cell transmission system than in the supernatant-mediated system. PrPSc was more efficiently transmitted from adherent spleen cells to neuronal cells than from floating spleen cells. The adherent spleen cells were composed of macrophages (80%), dendritic cells (8%) and follicular dendritic cells (3%), indicating that macrophages play an important role in PrPSc transmission from immune cells to neuronal cells. Although PrPSc in the immune cells used as donor cells was gradually degraded, the PrPSc transmitted to neuronal cells was observed by Western blot analysis. Investigation of the mechanism of PrPSc transmission between cells represents an important step towards understanding the pathogenesis of prion diseases.